In the related art, a sensor that transmits, when a fire is detected, a fire signal to a receiver and causes the receiver to output a fire alarm, is detachably attached to a sensor base disposed on a ceiling surface in a monitoring area. When the sensor is periodically inspected, there may be a case in which the sensor is detached from the sensor base and the detached sensor is disassembled to clean the inside.
In a sensor of the related art, for example, as described in Patent Document 1, a sensor main body is installed on the inside of a sensor cover, and when cleaning of the sensor is performed, a work of detaching the sensor main body from the sensor cover is performed.
In an attachment structure in which the sensor main body is installed on the inside of the sensor cover, for example, a fitting member is provided to stand on a plurality of positions on the outer circumference side of and the inside of the sensor cover, toward the opening of the cover. In the attachment structure, a fitting receiving member is provided on the sensor main body opposite the fitting member. The attachment structure is configured such that, when assembly in which the sensor main body is aligned to and inserted into the sensor cover is performed, the fitting member and the fitting receiving member are fitted and fixed to prevent detachment.